this is my first post so please excuse my ignorance. just bought 2009 hhr and have a ton of questions. first and foremost i love the way it drives when its right. problem is engine reduce in power warning comes on /svc esc/wervice traction. then its not so good.i can reset computer and its fine untill i shut it offf then warning comes back and runs bad......any ideas

 

Welcome to the site!!!

Mine did that same thing when I first bought it, It had the original battery in it so I decided to replace the battery. I havent had it happen to me again.

 

Welcome to the site.
First off you need to determine the reason for the CEL(check engine light) and the code it is showing. The computer is telling you that something is wrong and needs to be serviced. One of your local parts stores can pull the codes for you if you do not have a scanner.
Resetting the computer is just erasing the code set memory. Not the way to handle the problem. Kind of like resetting a tripped electrical breaker without determining why it tripped. Not a good idea.
Once you get the codes, if you need help figuring out the problem, the folks here will be glad to help.

 

Welcome !!!

 

 

........ and once you get that CEL code as firemangeorge noted, check this thread for a breakdown on the code itself - https://www.chevyhhr.net/forums/problems-service-repairs-42/list-diagnostic-trouble-codes-2008-2010-hhr-14259/

 

P0449 Evaporative Emission (EVAP) Vent Solenoid Control Circuit

 

a quick search of the forum for P0449 gave several links including this one which would be a good starting point:
https://www.chevyhhr.net/forums/show...ighlight=P0449

 

When I had that one, it was because I forgot to plug the electrical connection back in on the solenoid.